At present, apertured gaskets are provided with supplemental seals around apertures or in association with such apertures. Such supplemental seals may comprise embossments, such as those shown in Gorsica U.S. Pat. No. 3,053,544. Such embossments are sometimes filled with additional sealant materials, such as shown in U.S. Pat. No. 3,721,452 and German Pat. No. 819,177. Other patents, such as U.S. Pat. No. 4,213,620, show the compression of a gasket body except in localized zones to leave elevated portions for purposes of effecting a seal. Other patents disclose the coating of gasket surfaces, presumably by any type of coating process, see, for example, British Pat. No. 899,552.
Still other supplemental seals are printed patterns, such as annular patterns. Printed patterns are typically provided by the silk-screening of the gasket surface with the desired pattern, as is shown by Hillier U.S. Pat. No. 3,477,867. Filling embossments by a silk-screening process is shown in U.S. Pat. No. 4,140,323. Although silk-screened seals have become very important adjuncts to effective gaskets, the process is a relatively expensive one.
It would be of advantage to utilize supplemental sealing materials or supplemental seals which produce an effective sealing adjunct, but at a substantially lower cost.